According to its first aspect, this invention relates to a process for producing an industrially useful polymeric electrolyte complex by radiation-initiated graft copolymerization.
Polymeric electrolyte complexes, also known as "polyion complexes", have polycations and polyanions associated by ionic crosslinking so as to form a gel. Included within a class of polyion complexes that have been studied comprehensively for the possibility of practical applications are those which are formed from poly(styrenesulfonic acid) salts and poly(vinylbenzyltrimethyl ammonium) salts. These complexes are produced by mixing dilute solutions of the two components and they are then coated onto films by a casting method using a three-component solvent system composed of water, a polar solvent and a low-molecular weight salt, or onto other materials by a dip casting method. The complexes can also be produced by dipping sodium styrenesulfonate SSS in a particulate poly(vinylbenzyltrimethyl ammonium chloride) (VBTAC) resin and then polymerizing the mixture. The complexes produced by this method are used as snake cage resins.
The polyion complexes produced by these conventional methods have problems with physical properties as exemplified by low heat resistance, as well as by stiffness and brittleness in a dry state due to the lack of flexibility. Furthermore, when those complexes are coated onto substrates such as woven or nonwoven fabrics, their interstices are filled with the complexes and it often occurs that the substrates fail to exhibit their characteristics to the fullest extent. With a view to solving the afore-mentioned problems associated with physical properties and processability, one may attempt to attach styrene, chloromethylstyrene, vinylbenzyl dialkylamine or other monomers onto shaped substrates such as woven fabrics, nonwoven fabrics and nets by radiation-initiated graft polymerization and then introduce a quaternary ammonium group and a sulfone group into the polymer. However, this approach involves certain problems such as the occurrence of a side reaction due to the introduction of functional groups and the difficulty in controlling the amount of functional groups being introduced.